1. Field of the Invention
The present invention relates generally to an accessory unit for a rotary door panel, and more particularly to an innovative one which is designed into an adjustable door closer.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
The so-called “door closer” is generally mounted onto the rotating shaft seat of a rotary door panel to control the closing speed of the door panel.
In view of the shortcomings of traditional door closer structures wherein only spring force is used to control the closing speed of door panel with excessive or insufficient resistance or inadequate adjusting function, an adjustable door closer structure has been developed accordingly. As per structural principle of said adjustable door closer for controlling the closing speed of door panel, the spring force is combined with the backflow channel of lubricating oil and throttle valve to adjust the closing speed of door panel via the resistance of the lubricating oil.
Yet, there still lack of some shortcomings in the conventional structure of said adjustable door closer, which are illustrated in the following figures. FIGS. 1-3 depict a conventional adjustable door closer, wherein a hollow pedestal 10 is fitted with a first chamber 11 and second chamber 12 filled with lubricating oil. One end of the first and second chambers 11, 12 is connected with an actuating groove 13, which is provided with an actuating seat 14 and a driving shaft 15 driven by the door panel. The driving shaft 15 is linked to a cam 16 that can drive the actuating seat 14 to generate translational movement during its rotation. Moreover, a first piston 113 and a first spring 115 are installed into the first chamber 11. The first piston 113 is linked to the actuating seat 14 via a first link rod 116. A second piston 123 and a second spring 125 are installed into the second chamber 12. The second piston 123 is linked to the actuating seat 14 via a second link rod 126. In case of translational movement of the actuating seat 14, the first and second pistons 113, 123 can be driven simultaneously to compress the first and second springs 115, 125 to accumulate spring force. Of which, a one-way check valve 117 is set on the end surface of the first piston 113. Moreover, a first connecting duct 21 and second connecting duct 22 are arranged separately onto the partition wall 17 between the first and second chambers 11, 12 so as to connect the first and second chambers 11, 12. Of which, a first regulating valve 213 is set at middle position of the first connecting duct 21, and a second regulating valve 223 set at middle position of the second connecting duct 22, so as to regulate the flow speed of lubricating oil in the first and second chambers 11, 12 and control the closing speed of the door panel. Moreover, a cutting plane 18 is formed laterally on the periphery of the first piston 113, and a through-hole 180 penetrates radially the first piston 113 from the cutting plane 18, such that lubricating oil in the second chamber 12 could flow to the first piston 113 and actuating groove 13 through the first connecting duct 21, cutting plane 18 and through-hole 180.
However, it is still observed in actual applications that, the first and second connecting ducts 21, 22 linking the first and second chambers 11, 12 along with a through-hole 180 are set on the partition wall 17, so five holes will be formed on the first and second chambers 11, 12, leading to higher manufacturing cost and defects. On the other hand, the cutting plane 18 set on the periphery of the first piston 113 must be molded through secondary processing after molding of the first piston 113, leading also to increase of manufacturing cost; besides, both end surfaces of the first and second pistons 113, 123 are of closed surfaces, so the substrate is made of solid metal with higher material cost. On the whole, there is still a room for innovative development due to shortcomings of conventional adjustable door closer such as higher manufacturing cost and poor economic benefits.
Thus, to overcome the aforementioned problems of the prior art, it would be an advancement if the art to provide an improved structure that can significantly improve the efficacy.
Therefore, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products.